The addition of the polynomials x⁴ - 3x + 1, 4x² - 2x + 8, x³ - 9 in descending powers of x is x⁴ + x³ + 4x² - 5x.
Adding the polynomial
(x⁴ - 3x + 1) + (4x² - 2x + 8) + (x³ - 9)
= x⁴ - 3x + 1 + 4x² - 2x + 8 + x³ - 9
= x⁴ + x³ + 4x² - 3x - 2x + 1 + 8 - 9
= x⁴ + x³ + 4x² - 5x
Therefore, the addition of the polynomials x⁴ - 3x + 1, 4x² - 2x + 8, x³ - 9 in descending powers of x is x⁴ + x³ + 4x² - 5x.
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